Allow to build without GlideHQ support
Some systems don't have the required boost support and would not be able to
compile glide64 without adding a lot of new dependencies to their build
environment.
Remove warning about wxDynamicLibrary
The Glitch64 library is now part of glide64mk2 and it doesn't need to check the
symbols of an external library. Therefore, no wxDynamicLibrary is needed.